Predation
வேட்டையாடுதல்
Nature is not a playground; it is a battlefield of energy transfer. If you think predation is merely killing, you have already lost marks in the exam. It is the primary mechanism for maintaining species diversity in a community.
The idea
Predation is an interspecific interaction where the predator kills and consumes the prey. It serves as a conduit for energy transfer across trophic levels. Predators keep prey populations under control, preventing overexploitation of resources. Without predators, prey species would achieve high population densities and cause ecosystem instability.
Why it matters
It serves to control prey population density and maintain ecosystem stability by preventing any single species from over-dominating.
NEET lens
NEET focuses on the 'prudent' nature of predators and the 'biological control' aspect. Memorize the Pisaster starfish example from the rocky intertidal communities of the American Pacific Coast. Questions often test how predators prevent prey species from becoming extinct through competitive exclusion. Do not confuse predation with parasitism; predation involves immediate death.
Clinical significance
In human biology, consider the immune system as a predator-prey model. Phagocytes act as predators, engulfing and destroying pathogenic bacteria to maintain homeostasis. If this 'predation' fails, the host suffers from uncontrolled systemic infection and sepsis.
Introduction
Predation is an interaction where one species (predator) kills and eats another (prey) — (+, −). In a broad ecological context, herbivores are also predators of plants.
Core concept
Roles of predators (NCERT): (i) act as 'conduits' for energy transfer across trophic levels; (ii) keep prey populations under control — e.g. when the prickly pear cactus was introduced into Australia in the early 1920s, it spread rapidly; it was brought under control only after a cactus-feeding predator (a moth) from its natural habitat was introduced; biological control methods are based on this ability; (iii) help maintain species diversity by reducing the intensity of competition among competing prey species — e.g. in the rocky intertidal communities of the American Pacific coast, the starfish Pisaster is an important predator; when all starfish were removed, more than 10 species of invertebrates became extinct within a year because of interspecific competition. Prey defences: camouflage (cryptic colouring) in some insects and frogs; distastefulness — the Monarch butterfly is highly distasteful because of a special chemical acquired by feeding on a poisonous weed in its caterpillar stage; plants have thorns (Acacia, cactus) and chemicals (Calotropis produces highly poisonous cardiac glycosides).
Go deeper
If a predator is too efficient and overexploits its prey, the prey might become extinct, and then the predator too. This is why predators in nature are 'prudent'.
From Class 10
A tiger hunting a deer is predation — the tiger gains and the deer loses. Predators also keep prey numbers from growing out of control.